• Hall effect thuster scaling
• Hall effect thruster
• electric propulsion
• characterization campaign
• 20kW power
• low thrust
• space propulsion

The need of large payloads in space plays a crucial role for future space exploration. This issue can be tackled using large chemical rockets if short transfer times are requested by the mission. The other promising option is electric propulsion, which enables significant propellant mass savings, resulting in larger payloads.
The use of this technology has been limited in the past by the power avalilable on spacecrafts. Very high power electric propulsion has been typically associated with futuristic high power sources, such as nuclear reactors. However, recent developments in the field of solar arrays technology allowed to increase the available power on board modern spacecrafts. This trend is clearly expressed in last geostationary platforms, which reached and even exceeded the 20kW of produced power.
Moreover, among different electric propulsion systems, Hall effect thrusters represent a versatile solution, due to their easy scalability and good performance in terms of thrust efficiency and specific impulse.
In the present work, after a brief introduction on space propulsion, a short description of the working principles of Hall thrusters is provided. Then, an extensive review of very high power Hall thrusters (>10kW), developed and tested up to the present date is presented.
In order to design a new 20kW-class thruster, the scaling method developed by SITAEL in the past years was used to describe high-power configurations. The method, which was first validated against the experimental data of a reviewed thruster, allowed the preliminary assessment of the thruster performance also for non-conventional designs. A thruster configuration, with reduced size compared to existing models of the same power, was then selected for manufacturing.
Nominal conditions in terms of thrust and specific impulse, obtained from the scaling process, are taken as a reference to analyse different mission scenarios. In this ancillary part of the work, simple examples of near-term and long-term scenarios are provided.
Finally, performance data of the new thruster are presented. The thruster performed well in terms of specific impulse and thrust efficiency, especially at high voltages. In addition, at the nominal discharge power of 20kW, it demonstrated thrust levels higher than 1N and a maximum thrust efficiency of approximately 63%. As a result, the new thruster represents a promising solution for deep space esploration, and, in near term scenarios, for Earth-Moon cargo missions.